Films on which cells are cultured are used in the treatment of skin wounds such as for example wounds caused by severe burns or mechanical or chemical injuries or in diseases where extensive loss of skin occurred. In cases of acute extensive skin loss treatment generally involves two phases. In the first phase the requirements for a film material are directed towards short term requirements such as controlling moisture flow through the wound and shielding from infectious agents. In the second stage long term effects are considered such as non-antigenicity, and skin regeneration.
Development of such materials is in the direction of multilayer materials of increasing complexity as described in, for example, EP 0 686 402, WO 03/101501. Many patent applications disclose the use of porous collagen or gelatin matrices or sponges that require the formation of collagen fibrils and forming of a porous network, for example by freeze drying, before crosslinking the porous matrices as in for example EP 0 177 573, EP 0 403 650, EP 0 403 650, EP 0 411 124, EP 0 702 081, U.S. Pat. No. 4,016,877 and U.S. Pat. No. 4,294,241.
In applications for wound treatment fibroblast and keratinocyte layers are cultured on a collagen or gelatin matrix. In such cultures the fibroblast cells and/or keratinocyte cells are usually actually embedded in the matrix material, due to the porous nature of the collagen or gelatin matrix. EP 0 243 132 describes culturing of fibroblasts on an insoluble collagen film and the subsequent culturing of keratinocytes on top of the fibroblast layer, but has as a drawback that the fibroblast and keratinocyte layers are in contact.
WO 80/01350 discloses production of a living tissue by culturing keratinocytes on a collagen layer in which fibroblasts are imbedded, but this also means that the fibroblast layer and the keratinocyte layers are in contact.
WO 91/16010 describes a complex material based on a non-porous collagen gel that is stabilized by iodine and which is laminated on top of a porous collagen sponge containing fibroblasts. Keratinocytes are cultured on top of the stabilized collagen gel. The porous collagen sponge is crosslinked to prevent too fast biodegradation.
Use of recombinant collagen or gelatin is disclosed in e.g. WO 00/09018 but describes the formation of crosslinked sponges of collagen fibrils. WO 04/78120 also discloses porous structures from recombinant collagen.
Films are also used to test for example allergic reactions to topical applications comprising medicines, pharmaceuticals or cosmetics.
In spite of the above described materials there remains a need for alternative films for culturing cells that are suitable for treatment of wounds involving the loss of skin.